linux-kernel - Re: [RFC v1 05/26] x86/traps: Add #VE support for TDX guest

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20210208164639.GB365765@tassilo.jf.intel.com>
Date:   Mon, 8 Feb 2021 08:46:39 -0800
From:   Andi Kleen <ak@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [RFC v1 05/26] x86/traps: Add #VE support for TDX guest

> > > So what happens if NMI happens here, and triggers a nested #VE ?
> > 
> > Yes that's a gap. We should probably bail out and reexecute the original
> > instruction. The VE handler would need to set a flag for that.
> > 
> > Or alternatively the NMI always gets the VE information and puts
> > it on some internal stack, but that would seem clunkier.
> 
> The same is possible with MCE and #DB I imagine.

I don't think there are currently any plans to inject #MC into TDX guests. It's
doubtful this could be done securely.

#DB is trickier because it will happen every time, so simply reexecuting
won't work. I guess it would need the ve info stack, or some care in kprobes/kernel
debugger that it cannot happen. I think I would prefer the later.

-Andi